Multidimensional assessment of voice characteristics after radiotherapy for early glottic cancer

Objectives/Hypothesis: To assess voice characteristics of patients following radiotherapy for early glottic cancer through a multidimensional analysis protocol including vocal function and voice quality measures. Methods: Voice analyses were performed for 60 patients treated with radiotherapy (66 Gy/33 fractions, 60 Gy/30 fractions, or 60 Gy/25 fractions) for early T1 glottic cancer and 20 matched control speakers. There was a longitudinal group of 10 patients for whom data were collected before as well as 6 months and 2 years after radiation. Furthermore, data were collected for five separate groups of 10 patients each, before, 6 months after, 2 years after, 3 to 7 years after, and 7 to 10 years after radiation. Vocal function was investigated by means of videolaryngostroboscopy, phonetography, maximum phonation time, and phonation quotient measures. Voice quality was assessed by means of objective acoustical analysis and subjective perceptual ratings by trained raters. Results: Voice characteristics of patients were decreased before radiotherapy, improved after treatment, and became comparable to the voice characteristics of control speakers in at least 55% of the patients. Following radiotherapy, deviant voice quality was mainly negatively affected by increased age and stripping the vocal cord for initial diagnosis. Stroboscopy revealed that next to increasing age and stripping the vocal cord, continued smoking after treatment decreased vocal function following radio-therapy. Conclusion: Voices of patients diagnosed with early glottic cancer improved but did not normalize fully after radiotherapy. Stripping the vocal cord for initial diagnosis and continued smoking after treatment decreased voice characteristics. A multidimensional analysis protocol including perceptual and acoustical analysis of voice quality and stroboscopic analysis of vocal function is recommended to investigate voice characteristics following treatment for early glottic cancer.